1. Field of the Invention
The invention relates to an improvement in overhead rail scales which are used to weigh objects such as sides of meat, conveyed on a rail system.
2. Description of the Prior Art
Overhead rail scales form an integral part of overhead rail systems which are used to convey and weigh objects as they are transported across the rail system. Such scales are commonly used to weigh large sides of meat as they are moved by an overhead rail system from a loading dock to the butcher's block.
Rail scales are generally comprised of a "live rail", i.e., a vertically moveable rail that is in line, when at rest, with the fixed rail supported by the overhead rail system, and a pair of rail hangers fastened at each end portion of the live rail and connected to weight measuring means which are fixed to the overhead rail system.
In operation, the object to be weighed is moved along the rail system by means of a load carrying wheel assembly which rolls along the fixed rail and onto the live rail. When the object to be weighed is on the live rail, its movement is stopped and the weight of the object causes the live rail to deflect downwardly, causing a readout in the measuring gauge associated with the weight measuring means.
When the weight measuring means are load cells, it has been the common practice to align the load cells so that their cylindrical axes are parallel to the lateral axis of the live rail.
Conventional rail scales have, in general, performed satisfactorily but have experienced some problems in connection with installation and operation. Rail scales are difficult to calibrate and align with the fixed rail and as a result, about 7 to 8 hours are required to achieve a satisfactory alignment and calibration. In addition, the rail hangers at each end of the live rail become permanently deflected over the passage of time. This deflection introduces error into weighing measurements made by the scales and results in a slight misalignment in the live rail vis-a-vis the fixed rail.
Conventional rail scales also require the presence of a metal bar, referred to as a "check", to prevent any swaying of the live rail and rail hangers. The checks are generally connected to the bottom end portion of each rail hanger and to the rail support system.